As part of the National Cancer Institute's Smoking and Health Program, the study is an extension of the tobacco and health survey being conducted in six major cities in the United States and the International Agency for Research on Cancer in Cuba, and the European environment. The program continuation is of significance because the range of smoking productes in use by large and diverse human populations of Europe, and the range of incidence of lung cancer among these populations, permit strong comparisons with experience in the United States and Cuba. The project is urgently needed to provide a common (international) basis for measuring risk and clarifying the impact of alternative smoking products on differing human population segments. Data collection and analysis by strictly comparable methods ameliorate uncertainties attendant to past intranational studies and provide information of unique value in regard to smoking and health.